The present invention relates to a heater backed with a ceramic substrate (hereinafter referred to as "ceramic plate heater"), especially a ceramic plate heater having an excellent durability.
Generally, a ceramic plate heater is produced, by thick film-printing on a ceramic substrate a heating element pattern using a paste containing heat resistant metal such as platinum, platinum-rhodium, molybdenum, tungsten, etc., and by cofiring the ceramic substrate with the printed pattern. In this case, the ceramic substrate is a ceramic material formable by conventional means, such as sheet forming and extrusion molding into a desired form such as plate, cylinder, etc. And in case of using this kind of ceramic plate heater in a D.C. electric source, as is the case with the exhaust gas sensor of automobiles, heat is generated by passing electric current under an applied D.C. voltage to the heating element. However, it had a drawback that the heating element has a short life due to disconnections which are easy to occur in a high temperature atmosphere such as an exhaust gas.